An increasing body of evidence suggests that unfolding of globular proteins can lead to toxicity.1 Unfolded proteins can initiate protein aggregation and fibrillization by adopting a partially structured conformation. Such fibrillar aggregates can (slowly) accumulate in various tissue types and are associated with a variety of degenerative diseases. The term “amyloid” is used to describe these fibrillar deposits (or plaques). Diseases characterized by amyloids are referred to as amyloidosis and include Alzheimer disease (AD), light-chain amyloidosis, type II diabetes and spongiform encephalopathies. It has been found recently that toxicity is an inherent property of misfolded proteins. According to the present invention, this is the common mechanism for these conformational diseases.1 
A cross-β structure is a secondary structural element in peptides or proteins. A cross-β structure can be formed upon denaturation, proteolysis or unfolding of proteins.2 These secondary structure elements are typically absent in globular regions of proteins. The cross-β structure is found in amyloid fibers. Amyloid peptides or proteins are cytotoxic to cells. A cross-β structure includes stacked β-sheets. In a cross-β structure, the individual β-strands either run perpendicular to the long axis of a fibril or run in parallel to the long axis of a fibril. The direction of the stacking of the β-sheets in cross-β structures is perpendicular to the long fibril axis.